臺灣博碩士論文加值系統

正交分頻多工系統(OFDM)的高峰均值比是通訊系統中一個棘手的問題，此效應對行動裝置影響更甚。相較於正交分頻多工系統，單載波區塊傳輸系統(SCBT)有較低的峰均值比(PAPR)，並且可使用低複雜度的頻域(FD)等化。因此，第四代行動通訊LTE使用了單載波(SC)系統做為傳輸其上行傳輸的方式。除了有較低的峰均值比外，單載波系統還提供了多重路徑多樣性(multipath diversity)。通道中存在著越多條路徑，單載波系統能有越好的表現。
傳統用於單載波系統的塊狀引示訊號排列方式，在接收端進行通道估測時會造成資料佇列及時間延遲，為了解決該問題，我們在單載波系統中混合了時域的資料符號及頻域的引示訊號符號同時進行傳輸，如此一來便能使用梳狀引示訊號排列方式。我們亦比較了兩種信號等化的方式，一種為最小均方誤差等化，另一種則是使用Sphere Decoding (SD) 來達到最大概似解(ML)。在本論文的系統架構中，我們會盡量挑選適當的資料符號數量，以便使用快速傅立業轉換(FFT)來取代離散傅立業轉換(DFT)，借此提升系統的運算效率。最後，為了增強訊號在通道中的多重路徑多樣性，我們討論了兩種單載波區塊傳輸系統的訊號延展方式。

The Single-Carrier (SC) block transmission (BT) system enables low-complexity frequency-domain(FD) equalization, as the orthogonal frequency-division multiplexing (OFDM) system. Comparing the OFDM system, the SCBT system has much lower peak-to-average power ratio (PAPR), which is harmful to the communication system. The SC system is implemented in the uplink transmission of Long Term Evolution (LTE).In addition to low PAPR, the multipath diversity is another benefit of the SC system, while the OFDM system does not have the multipath diversity.
For the SCBT system, the data symbols are in the time domain while the pilot symbols are in the frequency domain. The conventional scheme uses the block-type pilot arrangement, which causes delays for channel estimation and data detection. In this thesis, we consider a channel estimation scheme based on the comb-type pilot arrangement to avoid the delay in data detection. We also consider two signal equalization method, minimum mean square error (MMSE) frequency equalization and maximum likelihood (ML) detection achieve by Sphere decoding (SD).Though the sizes of fast Fourier transform (FFT) and inverse FFT (IFFT) are different for the proposed scheme, we can choose proper sizes of FFT and IFFT to maintain the efficiency. We also consider the schemes with spreading codes, and study the effect of additional time diversity from the spreading codes.

Chinese Abstract I
English Abstract II
Acknowledgement III
Contents IV
List of Figures V
Chapter 1. 1
Introduction 1
Chapter 2. 3
2.1 SC-FDE System 3
2.1.1 Linear Precoded OFDM System 3
2.1.2 SC-FDE system 5
2.2 Channel Model 6
2.2.1 Modification of Jakes’ Rayleigh Fading Model 6
2.2.2 Multipath Model 8
2.3 Guard Interval 10
2.4 Channel Estimation 11
2.4.1 Pilot Setting 11
2.4.2 Peak-To-Average Power Ratio Performance 12
2.4.3 Estimation with Least-Squares Fitting – Channel Impulse Response 14
2.5 Signal Equalization 15
2.5.1 Minimum Mean Square Error Equalization (MMSE) 15
2.5.2 Sphere Decoding Algorithm for Near-ML Dictions 18
Chapter 3. 24
3.1 Walsh Hadamard Code 24
3.2 Spread Spectrum SC (SS-SC) 25
3.2 SC with Time Diversity Spreading 27
Chapter 4. 33
Conclusion 33
Bibliography 34

[1]E. Dahlman, S. Parkvall, J. Skold, and P.Beming, “3G Evolution-HSPA and LTE for Mobile Broadband. Oxford, U.K.: Acdaemic, 2007.
[2] M. Ghogho, V. P. Gil-Jimenez and A. Swami, “Multipath Diversity and Coding Gains of Cyclic-Prefixed Single Carrier Systems, ICASSP., pp. 2837-2840, Apr 2009.
[3]F. Pancaldi, G. M. Vitetta, R. Kalbasi, N. Al-Dhahir, M. Uysal, and H. Mheidat, “Single-Carrier Frequency Domain Equalization, IEEE Signal Process. Mag., vol. 25, NO 5, pp. 37-56, Sept. 2008.
[4]Z. Wang and G. Giannakis, “Wireless multicarrier communications-Where Fourier meets Shannon, IEEE Signal Process. Mag., vol.17, pp. 29-48, May. 2000.
[5]D. Falconer, R. Dinis, T. Matsumoto, M. Ran, A. Springer, and P. Zhu, WWRF/WG4/ Subproup on New Air Interfaces White Paper: A mixed Single-Carrier/OFDM Air Interfaces for Future-Generation Cellular Wireless Systems, Aug. 2003.
[6]Wireless World Research Forum, “Broadband Frequency Domain-Based Air Interfaces for Future-Generation Wireless Systems, WWRF Working Group 4, White Paper, Sep. 2005.
[7]L. Yunxin and H. Xiaojing, “The simulation of independent Rayleigh faders, IEEE Trans. Commun., vol. 50, pp. 1503-1514, 2002.
[8] S. H. Han, J. H. Lee, “An overview of peak-to-average power ratio reduction techniques for multicarrier transmission, IEEE Trans. Wireless Commun., vol12, pp. 56-65, Apr. 2005
[9]H. Vikalo, B. Hassibi, and P. Stoica, “Efficient joint maximum-likelihood channel estimation and signal detection, “ IEEE Trans. Wireless Commun., vol. 5, no. 7, July 2006.